Advanced Nanoemulsion Architectures for Precision Theranostics and Next-Generation Biomedical Translation

Nanoemulsions (NEs) are kinetically stable, thermodynamically unstable colloidal systems composed of nanoscale oil and aqueous domains stabilized primarily by surfactants and, where required, co-surfactants. Their small droplet size, large interfacial area, and tunable physicochemical properties provide opportunities to improve the solubilization, dispersion, permeation, stability, and bioavailability of poorly water-soluble and labile therapeutic agents. This review provides a comprehensive overview of the principles governing NE formulation and their evolving role in pharmaceutical and biomedical applications. Particular emphasis is placed on the selection and functional contribution of formulation components, high- and low-energy preparation approaches, scale-up and manufacturing considerations, critical quality attributes, physicochemical characterization, stability, and nano-bio interactions. The review further summarizes the application of NEs in oral, topical, ocular, pulmonary, parenteral, vaccine, immunological, and disease-specific drug delivery, together with emerging applications in theranostics and imaging. The available evidence indicates that NEs can enhance drug solubilization and delivery performance and can be engineered to incorporate therapeutic and imaging functionalities; however, the extent of targeting and clinical benefit remains dependent on formulation composition, biological barriers, disease heterogeneity, and the stage of translational development. Emerging artificial intelligence (AI) and machine-learning approaches show potential for formulation optimization, prediction of physicochemical and biological behaviour, and interpretation of complex imaging data, but their application to NE systems remains an evolving area constrained by data standardization, model transparency, reproducibility, and regulatory considerations. Major challenges to clinical translation include physical and chemical instability, limitations of passive and active targeting, manufacturing complexity, batch-to-batch reproducibility, scale-up, safety assessment, and regulatory requirements. Overall, NEs represent versatile platforms for pharmaceutical delivery and multifunctional biomedical applications, while further systematic validation, scalable manufacturing, standardized characterization, and clinically relevant evidence are required to translate promising laboratory findings into robust and clinically useful products.